Generally, a rotary electrical machine such as a generator motor and the like mounted on a hybrid vehicle, an electric vehicle and the like is configured so as to have a revolving-field type inner rotor so that a stator having a coil is arranged at an outer circumferential side and a rotor having a magnet is arranged radially inwardly of the stator. The stator of the rotary electric machine having the above-configuration generally includes a cylinder-shaped stator core having plural magnetic pole teeth, each of which protrudes in a radially inward direction, the coil, which is configured in a manner where a conductive wire is wound on each magnetic pole tooth, and an insulating bobbin, which is formed in a cylindrical shape and which is provided between each coil and each magnetic pole tooth so as to serve as an electric insulation. Furthermore, for example, disclosed in JP2009-261094A is a power collection/distribution structure of a rotary electric machine that is configured so that a bus ring, which is a ring-shaped conductor, is arranged axially outward of the stator core so that an electric power is supplied to each coil via the bus ring.
The power collection/distribution structure of the rotary electric machine disclosed in JP2009-261094A includes a number of bus rings corresponding to a number of plural phases for connecting coils having the corresponding phases, and plural holding members holding and fixing thereat predetermined portions of the bus rings in a circumferential direction thereof. Each of the holding members is formed in the same (identical) shape. According to the disclosure in JP2009-261094A, a number of components and costs relating to the configuration of the power collection/distribution structure may be reduced, so that a complicated work in a manufacturing process may be avoided. As a result, a productivity of the rotary electric machine may be increased.
Not only in the power collection/distribution structure of the rotary electric machine disclosed in JP2009-261094A, but also in general, a number of bus rings corresponding to a number of phases are provided at the rotary electric machine. Furthermore, plural holding portions are provided at the rotary electric machine in order to avoid each bus rings from contacting with each other. Still further, because an electric power is supplied to the rotary electric machine by means of a power cable, a terminal board for carrying the electric power needs to be provided at the rotary electric machine. Moreover, in order to connect the terminal board and the bus rings, bus bars need to be provided at the rotary electric machine. The bus bars are also arranged so as not to contact with each other. Additionally, in order to connect coil ends (winding ends) of the coils of different phases so as to form a neutral point, a ring-shaped neutral point bus ring may be adapted to the rotary electric machine. End portions of winding starts (coil starts) and the winding ends (the coil ends) of each phase coil are connected to predetermined portions of the corresponding bus ring by means of welding, screwing or the like.
Although the electric power is suppliable to each coil of the corresponding phase by using the corresponding bus ring, the bus bars and the like, a bus member tends to be expensive. Usually, the bus rings, the bus bars and the like are made of a copper wire, a copper plate and the like, which are relatively expensive. Furthermore, a bending process, a stamping process and the like and then, an insulation coating process need to be applied to the bus rings, the bus bars and the like. Still further, a number of components used for supporting the bus members such as the holding members and the like in order to ensure the electric insulation tends to increase, which may result in complicating an assembly operation. Additionally, a number of connecting points at which each end portion of each coil is connected tends to increase, which may also result in complicating a connecting operation. As described above, a relatively great number of components are used for the power supply portion in addition to the bus rings and the bus bars. Therefore, a relatively great number of manufacturing hours is necessary to manufacture the rotary electric machine.
Furthermore, a predetermined insulation distance (space) and a creepage insulation distance need to be formed in order to ensure an electrical insulation performance between each phase and between each ground. Accordingly, a size and a shape of each of the holding members and the like may not be flexibly changed, and an assembly of the rotary electric machine is strictly determined. Therefore, a size of the power supply portion in an axial direction tends to increase, which may further result in increasing a size of the stator.
A need thus exists for a stator for a rotary electrical machine which is not susceptible to the drawback mentioned above.